Re: [PATCH 6/6] arm64: dts: broadcom: bcm2712: Add GPU IOMMU and IOMMU cache nodes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Device tree node name unit-addresses do not match their `reg` property base addresses for `iommu4` and `iommuc`.
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--- Patch [6]: [PATCH 6/6] arm64: dts: broadcom: bcm2712: Add GPU IOMMU and IOMMU cache nodes ---
commit e5ff2e7025bd202974b9df36bf104c8bc98df79f
Author: Daniel Drake <dan@reactivated.net>

arm64: dts: broadcom: bcm2712: Add GPU IOMMU and IOMMU cache nodes

This commit adds devicetree nodes for the IOMMU and IOMMU cache on the
Broadcom BCM2712 SoC. It also configures the vc4 GPU to utilize the
newly defined IOMMU.

> diff --git a/arch/arm64/boot/dts/broadcom/bcm2712.dtsi b/arch/arm64/boot/dts/broadcom/bcm2712.dtsi
> index 761c59d90ffc9..ed3178db8acbd 100644
> --- a/arch/arm64/boot/dts/broadcom/bcm2712.dtsi
> +++ b/arch/arm64/boot/dts/broadcom/bcm2712.dtsi
> @@ -626,6 +626,20 @@ pcie2: pcie@1000120000 {
>  			status = "disabled";
>  		};
>  
> +		iommu4: iommu@5200 {

[Severity: Low]
This isn't a bug, but does this unit-address truncate the upper 32 bits
of the address defined in the reg property below?

The reg property specifies a base address of 0x10 0x5200, which evaluates
to 1000005200. Naming the node iommu@5200 instead of iommu@1000005200
typically triggers dtc simple_bus_reg warnings for mismatched unit
addresses.

> +			/* IOMMU for VC4 (HVS & MPL/TXP), Unicam, PISP-FE, MiniBVN */
> +			compatible = "brcm,bcm2712-iommu";
> +			reg = <0x10 0x5200 0x0 0x80>;
> +			#iommu-cells = <0>;
> +			brcm,iommu-cache = <&iommuc>;
> +			brcm,iova-window = /bits/ 64 <0xa00000000 0x100000000>;
> +		};
> +
> +		iommuc: iommuc@5b00 {

[Severity: Low]
Similarly, does this node name truncate the upper 32 bits?

The reg property base address is 0x10 0x5b00 (1000005b00), but the unit
address is written as 5b00.

> +			compatible = "brcm,bcm2712-iommuc";
> +			reg = <0x10 0x5b00 0x0 0x80>;
> +		};

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260712-bcm2712-iommu-submit-v1-0-80e10cdde2ea@reactivated.net?part=6